Medicare's alphabet soup of parts trips up almost everyone the first time. Missing the enrollment window can mean a permanent penalty, so this is one lesson worth reading before you turn 65, not after.
The Four Parts
Part A — Hospital
Inpatient hospital stays, skilled nursing, hospice. Usually premium-free if you paid Medicare taxes for 10+ years.
Part B — Medical
Doctor visits, outpatient care, preventive services. Has a monthly premium, income-adjusted.
Part C — Advantage
A private-insurer alternative bundling Parts A, B, and usually D into one plan.
Part D — Drug Coverage
Prescription drug coverage, sold through private insurers under Medicare rules.
When to Enroll (and the Penalty for Being Late)
Your Initial Enrollment Period is a 7-month window centered on your 65th birthday — it starts 3 months before, includes your birthday month, and extends 3 months after.
If you're still covered by a qualifying employer health plan (generally, a large employer) past 65, you can often delay Part B without penalty — but this needs to be confirmed with your specific plan, since not all employer coverage qualifies for this exception.
Medigap vs. Medicare Advantage
Once you have Original Medicare (Parts A & B), most people add one more layer to handle the gaps — deductibles, coinsurance, and the fact that Original Medicare has no out-of-pocket maximum:
Medigap (Supplement)
- Works alongside Original Medicare
- Higher monthly premium, but very predictable costs
- Broad access to any doctor accepting Medicare
Medicare Advantage (Part C)
- Replaces Original Medicare with a private plan
- Often lower or $0 premium, but network restrictions
- Usually includes drug coverage and extra benefits
Key Takeaways
- Part A covers hospital care, Part B covers medical care, Part C is a private all-in-one alternative, Part D covers drugs.
- The initial enrollment window is 7 months around your 65th birthday — missing it (without qualifying employer coverage) means a permanent penalty.
- Medigap adds predictable-cost supplemental coverage alongside Original Medicare; Medicare Advantage replaces it with a private network-based plan.
Check Your Understanding
Three quick questions — no grades, just a gut check before you move on.
1. What does Medicare Part A primarily cover?
2. What happens if you miss your initial Medicare enrollment window without qualifying coverage?
3. What's a key trade-off of choosing Medicare Advantage over Medigap?
Do This This Week
Reading is step one. Here's what actually moves the needle: